It is a standard present practice in the making of a ceramic substrate for electric components, first to effect briquetting of base ceramic powders under high pressure to form a green self-supporting substrate. The green substrate is coherent, relatively rigid, and will not readily crumble or fall apart before firing. The substrate is also apertured and its edges are frequently grooved. The product is fired, causing the compacted ceramic particles to become sintered together and become a rigid self-supporting product. Specifically, the ceramic content is made up of electrically non-conductive powders in the form of alumina, aluminum silicates, kyanite, silliminite, etc., the only requirement being that the particles must be of relatively uniform size, must be compactible, relatively water free, and possesses sufficient strength so that the product will remain coherent until firing. These fired substrates then have various resistance films and conductive paths printed or silk screened onto the surface and fired to effect bonding thereto.
Frequently, substrates vary in size, density, and weight since it is not possible to obtain absolute uniformity of particle size, and further because water content and flowability of powders introduces variations of size and density in the resulting briquette, even though the mold cavity remains the same.
Where there is substantial change in the density, weight and size of the briquette, the operator must be relied upon to make the necessary manual adjustments to the size of the mold cavity in order to reestablish the standad weight, size and shape of the desired briquette. Manual adjustment depends too much upon the skill of the individual operator and frequently necessitates interruptions of the briquetting operations for adjustment. Manual adjustment of the die cavity is too gross and too susceptible to individual judgment. As a result, in long runs, the briquettes deviate substantially from standard weight, size, and density.